occupancy sensor

[13.2.2] NOTE: This term was added in RP-16-17 Addendum 1. A control device that detects occupant presence and automatically turns luminaires and/or other equipment on and, after a preset delay during which no presence is detected, turns them off. Also called a motion detector. Read More

spatial daylight autonomy (sDA)

[10.5.17] NOTE: This term was added in RP-16-17 Addendum 1. A measure of daylight illuminance sufficiency for a given area, reporting a percentage of floor area that exceeds a specified illuminance (e.g., 300 lux) for a specified percentage of the analysis period.*   *  Illuminating Engineering Society. IES Approved Method: Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE). New York: IES; 2012. (IES LM-83-12). Read More

light trespass

[11.7.1] NOTE: This term was added in RP-16-17 Addendum 1. The encroachment of light, typically across property boundaries, causing annoyance, loss of privacy, or other nuisance. Read More

reflected direct luminaire

[10.3.14] NOTE: This term was added in RP-16-17 Addendum 1. A class of luminaires that make use of light reflecting off the interior surface of a recessed housing from concealed or obscured sources. Typically, these luminaires, which are similar in performance to lensed or diffused luminaires, have perforated metal baskets backed with diffuse acrylic to hide the lamps from direct view and to direct light onto the upper reflector surface. The upper reflector is commonly a smooth surface with a… Read More

track lighting

[10.3.15] NOTE: This term was added in RP-16-17 Addendum 1.  A lighting equipment system consisting of an electrified power channel (track) and removable luminaires (lamp holders, track heads) that can be mechanically attached anywhere along the power channel.  The luminaires can be repositioned and re-aimed as desired. Read More

annual sunlight exposure (ASE)

[10.5.16] NOTE: This term was added in RP-16-17 Addendum 1. In daylighting: The fraction or percentage of the horizontal work plane that exceeds a specified direct sunlight illuminance level more than a specified number of hours per year over a specified daily schedule with all operable shading devices retracted.*   * Illuminating Engineering Society. IES Approved Method: Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE). New York: IES; 2012. (IES LM-83-12). Read More

bidirectional scatter distribution function (BSDF)

[7.2.2] NOTE: This term was added in RP-16-17 Addendum 1. The general mathematical function or matrix of data that describes the directional scattering of light by a surface or complex glazing system through both reflection and transmission across input and output angles. In practice, this phenomenon is usually split into the reflected and transmitted components, which are quantified in a bidirectional reflectance distribution function (BRDF) and bidirectional transmittance distribution function (BTDF). Read More

visible transmittance

[7.5.3.17] VT or Tvis NOTE: This term was added in RP-16-17 Addendum 1. The fraction of incident luminous flux that is transmitted through a material. In daylighting: The fraction of luminous flux in the solar spectrum that is transmitted through a material or glazing system.   Also known as visible light transmittance (VLT). Read More

colorimeter

[8.5.1] NOTE: This term was added in RP-16-17 Addendum 1. An instrument that measures color in units specific to a color space such as the CIE 1931 Chromaticity Diagram, the CIE 1964 Chromaticity Diagram, CIELAB, or CIELUV. See also CIE standard chromaticity diagram, CIE (L*a*b*) uniform color space, and CIE (L*u*v*) uniform color space. Read More

center-beam candlepower (CBCP)

[8.6.4.3] NOTE: This term was added in RP-16-17 Addendum 1. The luminous intensity along the geometric centerline of a directional light source. The assumption in application is usually that the centerline candlepower is also the maximum candlepower.  Also called center-beam intensity. Read More